Evolution Of Dusty Plasmas In Magnetic Field

Dusty plasma exists widely in space and plays an important role in laboratory research and semiconductor manufacturing.Dusty plasma consists of dust particles,ions,electrons,and unionized neutral gas molecules(particles).Because the mobility of electrons is much higher than that of ions,dust particles are generally negatively charged.Two important characteristics of dusty plasma are that dust particles are highly charged and their charges vary with plasma parameters.Interactions between charged dust particles in dusty plasma systems are described by the modified Yukawa interaction potential.The Yukawa potential consists of long-range attractive potential and short –range repulsive potential,both of which compete with each other.When the distance between particles is large,the interaction potential is attractive,if not it is repulsive.In this thesis,the dynamic response of dusty plasma system to external magnetic field is numerically studied by molecular dynamics method.It is found that clusters composed of charged dust particles can exist in liquid phase or crystal.When the external magnetic field is applied,the transport process of charged dust particles will change.Adding the external magnetic field and simple harmonic force field at the same time,the dust particle trajectory will be a Petal shape(at this time,all particles in the system converge into a circular crystal).The existence of magnetic field always affects the cyclotron motion of dust particles,and the existence of simple harmonic force field is the guarantee for the crystallization of dust particles in the system.Through the study of the static structure factor of the system,the increment of the external magnetic field does not affect the structural stability of the system in the presence of simple harmonic force field.Finally,we study the velocity autocorrelation function to analyze the influence of magnetic field change on the velocity correlation of dust particles.The results show that the larger the magnetic field is,the higher the velocity autocorrelation between charged particles is in their steady state.